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Weigh 2 coins vs 2 coins.
If the result is equal then the coin left out must be the 32g coin.
If the result is unequal then the heavy side must have at least one 33g coin and the light side must have at least one 31g coin. Choose a side and compare those two coins.
If choosing the heavy side then an unequal result means that the heavier coin is 33g and an equal result means both coins are 33g. Similar logic applies to finding a 31g coin from the light side. |
